1. Field of the Invention
This invention relates to a process for producing an improved alumina-zirconia composite sintered material which is useful for employment in structural materials, refractorial materials, erosion resistance materials, cutting tool materials, grinding and polishing materials, etc.
2. Description of the Prior Art
In the prior invention, a process for producing an alumina-zirconia composite sintered material was invented [Japanese Patent Public Disclosure (Laid-Open Publication) Nos. 100412/1987 and 51369/1989]. These sintered materials (so called ceramics) made by this method are twice as strong as alumina ceramics in bending and toughness strength.
Practical applications of this material are suitable for use in tough conditions of rapid temperature change and/or excess corrosion, both deterimental to metals. But in these environments, if a rapid volume change occurs at a point of phase-transformation from low temperature phase to high temperature phase or the reverse, the material becomes weakened if it contains a non-stabilized zirconia and so it weakened the material. As the volume change occurs, the grain boundaries in a sintered material crack, which can cause the occurrence of wear at rubbing and at impacting.